Turbine propulsion installations for controllable pitch propellers



May 30, 1961 N. J. LIAAEN 2,986,221

TURBINE PROPULSION INSTALLATIONS FOR CONTROLLABLE PITCH PROPELLERS I Filed Jan. 8, 1957 2 Sheets-Sheet 1 FIG].

INVENTOR NILS I. L IAAEN ATTORNEYS y 961 N. J. LIAAEN 2,986,221

TURBINE PROPULSION INSTALLATIONS FOR CONTROLLABLE PITCH PROPELLERS Filed Jan. 8, 1957 2 Sheets-Sheet 2 lNVENTo NM 1. LIAAEN 20 a M, MW Wm United States Patent TUR INE PROPULSION INSIALLA'I'IONSFOR CDNFROLLABLE PITCH .PROPELLERS NiIsJOhannesLiaaen, Borgundveien 17B, AlesunmNorwax Fll'ed'llanz 8; 1957, Set-Nb. 633,018

2 Claims. (Cl. 170-135.75)

The present invention relates to installations for turbine propulsio'n of controllable pitch propellers.

In a vessel equipped with a controllable pitch propeller the number of revolutions of the propeller is increased when the pitch of the propeller is changed from a higher to a smaller value. The reason is that in the first moment upon a pitch reduction, the speed of the vessel is unchanged and the volume of water passing the propeller consequently equals to that passing the same prior to the pitch reduction. In order to make the same volume of water pass through the propeller in spite of the reduced pitch, the number of revolutions of the propeller is forced to increase. In turbine propulsion installations, the number of revolutions is increased above the allowable value when the pitch is heavily reduced from high loads. This is due to the fact that in a turbine the kinetic energy is in its entirety stored in the rotating masses in contradiction to that which is the fact in a pisto'n engine. Further, the steam or gas present in the turbine will also, when the governor has closed the supply as a consequence of a too high number of revolutions, give off its energy to the propeller shaft during the expansion. Finally, turbines have a high mechanical efliciency, to the effect that the friction losses are of less importance than in the case of a piston engine.

For the purpose of remedying this deficiency, the instal lation according to the invention is provided with a turbine shaft brake which is engaged and disengaged in dependence upon the number of revolutions of the turbine, i.e. the turbine load.

Four embodiments of the inventions are diagrammatically shown in Figures 1, 2, 3 and 4, respectively, of the accompanying drawings.

In all the figures of the drawings, 1 is a controllable pitch propeller, 3 a turbine and 2 a reduction gear installed between the turbine and the propeller.

In the embodiment shown in Figure 1, 4 is a hydraulic brake which is charged and discharged with liquid under the control of a slide '5 from a head tank 6, the slide 5 having an outlet to a drain tank 7. The fluid is pumped back from the drain tank to the head tank by a pump 8. The slide 5 is operated by a servo motor 9 under the control of a governor 10 connected to the shaft of the turbine 23.

In Figure 2, 11 is a fluid filled hydraulic brake and 12 an electromagnetic clutch arranged between the brake and the turbine shaft and operated by a contactor 13 under the control of the governor 10.

In the embodiment shown in Figure 3, the references 11, 12 and 13 are of the same meaning as in Figure 2, but 18 is an electromagnetically operated switch and 19 a torque-meter of the so-called torductor type.

In the embodiment shown in Figure 4, 14 is a turbine wheel mounted on the shaft of the turbine 3 and serving as a brake wheel, the driving means being supplied to the brake wheel through a conduit 15 under the control of a servo valve 16 in dependence upon the swing of the governor 10. 17 is a drive means supply conduit.

.thefollowing manner:

When .the turbine. is. racing, the governor 10. is. swung and the servo motor 9 raises the slide 5 to theeffectthat fluid is. supplied. from the head. tank.6 to the-brake 4 at the same time as the slide-.5 is closing. the outlet from. the brake 4 to the drain tank 7.

Thereby; the brakeisbrought'into actionand the number of revolutionsof .the turbine is reduced, whereby the slide 5 is again lowered so as to reclaim the supply from the head tank'and reopen -the-outletto'thedrain tank, wherebythe'brake is discharged and the brake effect interrupted.

In the installation shown in Figure 2, the brake 11 is continuously fluid filled, but is normally disengaged from the turbine shaft. When the number of revolutions of the turbine shaft is rising above an allowed value, the governor 10 is swung and closes a contact, whereby the contactor 13 is closing the actuating circuit of the electromagnetic clutch 12, to the effect that the fluid filled hydraulic brake 11 engages the shaft and brakes the turbine. As soon as the number of revolutions of the turbine shaft is reduced and the swing of the governor is reduced, the making contact of the contacto'r 13 is broken and the clutch 12 disengaged.

Instead of the hydraulic brake shown and described, other brakes obviously may be used, such as electromagnetic or electrodynamic brakes.

In the installation shown in Figure 3, the engagement of the brake is effected in dependence upon variations in the torque stress in the turbine shaft appearing when the propeller pitch is reduced. The function is based upon the fact that the direction of an axial magnetic flux in the surface of the shaft is deviated when the torque stress is varying, such deviations in the flux direction being utilised in a so-called torductor 19 for the generation of an electric.

voltage which is applied to the electromagnetic switch 18, the axial magnetic flux being produced by the torductor itself, such as by the aid of a U-formed iron core magnetised by alternating current. The poles of this core is located a few millimeters away from the surface of the shaft. At right angles to this core and combining to form a measuring head is a similar U-formed iron core like wise equipped with a winding. A variation in the load or stress condition of the shaft is affecting the balance be tween the two fluxes produced by the two magnets thereby deviating the direction of the combined fluxes, deviations which are utilised for measuring or actuating purposes. The device described does not form any part of the present invention. With the arrangement described, the engagement of the brake is elfected at an earlier point of time than when effected by means of a governor acting in dependence upon the number of revolutions, due to the fact that the stress variations are appearing earlier than the variations in number of revolutions.

The installation shown in Figure 4 is particularly adapted for use in connection with steam turbines and is functioning in such a manner that when the governor 10 is swinging due to a too high number of revolutions, the governor is causing a servo controlled valve 16 to open a steam supply conduit 15 whereby the brake wheel 14 is engaged and brakes the turbine 3. As soon as the number of revolutions is again reduced to an allowable value, the servo valve 16 is reclosing the steam supplyconduit 15, and the brake 14 is disengaged.

The term absolute value as employed in the appended claims, is intended to include the direction of transmission of the torque, that is, to express the fact that the sign of the torque is changed from plus to minus (or vice versa) when the propeller becomes a turbine.

I claim:

1. A turbine propulsion installation for marine ships;

comprising in combination, a turbine, a controllable pitch propeller, a shaft means interconnecting said turbine and controllable pitch propeller, a brake means coupled to said shaft means and a brake control means synchronized with said shaft means, whereby said control means are 5 connected to said brake means to apply and release said brake means upon variation of the turbine load caused by the change in pitch of said propeller.

2. The installation described in claim 1 wherein said brake means is a hydraulic brake. 10

References Cited in the file of this patent UNITED STATES PATENTS Sendtner Sept. 22, 1896 15 4 Bailey Ian. 16, 1917 Hutchison Apr. 19, 1927 Peterson Nov. 18, 1941 Reggio July 2, 1946 Sawyer July 27, 1948 Prince Apr. 3, 1951 Spurceon June 22, 1954 Bain Mar. 6, 1956 Amann Ian. 21, 1958 Peterson Mar. 11, 1958 Alishouse Sept. 2, 1958 Peterson Nov. 18; 1958 McDowell et al. July 7, 1959 

